Fuel-cell unit cell

1. A fuel-cell unit cell comprising:

(I) an electrode stack having

(a) a membrane-electrode assembly in which electrode catalyst layers are respectively laid on both surfaces of an electrolyte layer,

(b) a first gas diffusion layer laid on a first surface of the membrane-electrode assembly such that an outer peripheral edge portion of the first gas diffusion layer protrudes from an outer periphery of the membrane-electrode assembly, and

(c) a second gas diffusion layer laid on a second surface of the membrane-electrode assembly;

(II) a support frame disposed apart from the membrane-electrode assembly so as to surround the membrane-electrode assembly;

(Ill) a first separator that is laid on a side of the electrode stack on which the first gas diffusion layer is located, in contact with the first gas diffusion layer, and that is fixed to the support frame; and

(IV) a second separator that is laid on a side of the electrode stack on which the second gas diffusion layer is located, in contact with the second gas diffusion layer, and that is fixed to the support frame,

wherein, at a first part of the fuel-cell unit cell:

the fuel-cell unit cell has a bonding layer;

between the membrane-electrode assembly and a portion of the first gas diffusion layer on an inner side from the outer peripheral edge portion, the bonding layer bonds the membrane-electrode assembly and the portion together; and

the support frame and the outer peripheral edge portion of the first gas diffusion layer are bonded together by the bonding layer, and at least one of between the support frame and the first separator, or between the support frame and the second separator, the support frame and the respective separator are bonded together by the bonding layer; and

wherein, at a second part of the fuel-cell unit cell:

the second separator has a reactant gas flow passage;

a second cover plate is disposed between the second separator and the second gas diffusion layer, between the second separator and the outer peripheral edge portion of the first gas diffusion layer, and between the second separator and the support frame;

between the membrane-electrode assembly and the portion of the first gas diffusion layer on the inner side from the outer peripheral edge portion, the bonding layer bonds the membrane-electrode assembly and the portion together;

between the outer peripheral edge portion of the first gas diffusion layer and the second cover plate, the bonding layer is bonded to the second cover plate;

the support frame and the outer peripheral edge portion of the first gas diffusion layer are bonded together by the bonding layer, and at least one of between the support frame and the first separator, or between the support frame and the second separator, the support frame and the respective separator are bonded together by the bonding layer; and

the bonding layer is thus separated from the reactant gas flow passage of the second separator.

2. The fuel-cell unit cell according to claim 1 , wherein the support frame is disposed between the outer peripheral edge portion of the first gas diffusion layer and the second separator in a thickness direction of the fuel-cell unit cell.

3. The fuel-cell unit cell according to claim 1 , wherein the support frame is disposed apart from the first gas diffusion layer so as to surround the first gas diffusion layer.

4. The fuel-cell unit cell according to claim 1 , wherein, at the second part of the fuel-cell unit cell:

the first separator also has a reactant gas flow passage;

a first cover plate is disposed between the first separator and the first gas diffusion layer and between the first separator and the support frame;

between the support frame and the first cover plate, the bonding layer bonds the support frame and the first cover plate together; and

the bonding layer is thus separated from the reactant gas flow passage of the first separator.